The departure of Iñigo Martínez to Saudi Pro League side Al Nassr earlier this year saw coach Hansi Flick lose a key figure from last season's backline.
Barça currently have Pau Cubarsí, Ronald Araújo, Eric García and Andreas Christensen as options to play in the middle of the defence, but Flick has struggled to find a consistent pairing this season.
In recent weeks, with Araújo currently taking a mental health break and García playing in midfield, the German coach has even used left-back Gerard Martín as a centre-back.
Flick's reason for using Martín there is the benefits it provides for the team in possession when they can play out from the back with a left-footed player.
Barça, therefore, are scouring the market for a long-term partner for Cubarsí, who has been the most-used centre-back this season, and sources have told ESPN that Torres is a player that has always been on the club's radar because of his ability both on the ball and in the air.
The LaLiga leaders previously considered making a move for the Spain international when he was at Villarreal, but he eventually joined Villa in 2023 in a deal worth around €40 million ($47m).
Barça are aware that it won't be easy to deal with Villa, given he is a key player in Unai Emery's team, but sources have suggested to ESPN that Torres, whose contract in Birmingham runs until 2028, would listen to an offer to return to Spain should the Catalan club take a serious move to sign him.
However, Torres is not the only option Barça are considering in their bid to bolster a defence that has conceded 31 goals in 23 games in all competitions this season.
Barcelona also consider Nico Schlotterbeck
Sources previously told ESPN that Barcelona also have positive reports about Borussia Dortmund's Nico Schlotterbeck, whom they have followed since his breakthrough at SC Freiburg.
The Germany international has a contract until 2027 with Dortmund so could leave for a reduced price next summer if he does not renew, with several other big European clubs also monitoring his situation.
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Any move Barça do make will once again be conditioned by their financial situation as they strive to comply with LaLiga's financial fair play regulations, sources said.
They could potentially free up some space for signings next summer with the departures of some big earners, with both Christensen and Robert Lewandowski out of contract at the end of the season.
Sources said no final decision has been made on either Christensen or Lewandowski's futures beyond the end of the current campaign yet, but if the Danish defender does leave, it would only increase Barça's need to invest in a new centre-back.
